The gastrointestinal microflora has been shown to play a number of vital roles in maintaining gastrointestinal tract function and overall physiological health. For example, the growth and metabolism of the many individual bacterial species inhabiting the gastrointestinal tract depend primarily upon the substrates available to them, most of which are derived from the diet. See, e.g., Gibson et al., 1995. Gastroenterology 106: 975-982; Christl, et al., 1992. Gut 33: 1234-1238; Gorbach, 1990. Ann. Med. 22: 37-41; Reid et al, 1990. Clin. Microbiol. Rev. 3: 335-344. These finding have led to attempts to modify the structure and metabolic activities of the community through diet, primarily with probiotics, which are live microbial food supplements.
The best-known probiotics are the lactic acid-producing bacteria (i.e., Lactobacilli and Bifidobacteria), which are widely utilized in yogurts and other dairy products. These probiotic organisms are non-pathogenic and non-toxigenic, retain viability during storage, and survive passage through the stomach and small intestine. Since probiotics do not permanently colonize the host, they need to be ingested regularly for any health promoting properties to persist. Commercial probiotic preparations are generally comprised of mixtures of Lactobacilli and Bifidobacteria, although yeast species such as Saccharomyces have also been utilized.
There remains a need for the development of a highly efficacious, non-antibiotic-based therapeutic regimen which functions in acute treatment scenarios, as well as prophylactically to mitigate antibiotic-resistant pathogens (e.g., antibiotic-resistant enterococci) in both humans and animals.